Illuminated displays for alphanumeric and special characters are typically used in electronic devices and appliances. Examples include digital displays for time and other information typically present on microwave ovens and video cassette recorders. These displays typically have an opaque base with an opening that defines an outline of a letter, a number or a special character such as a symbol or punctuation mark. Light from an electrically-operated light source such as a light emitting diode (LED) is typically projected through the opening.
If the character being outlined is an open character such as the numeral “2” or the letter “L”, the illuminated display for that character closely represents a typeset version of that character and is aesthetically pleasing to the human eye. However, if the character being outlined is a closed character such as the letter “D” or the numeral “8”, the characters typically have a stenciled appearance that is not aesthetically pleasing to the human eye. A closed character encloses an inner member that must have a means for anchoring to the opaque base.
Some displays, for example, such as the widely used seven segment numeric display can be switched to represent any of several different characters. The seven segment display typically uses seven different straight line segments to form the numerals zero through nine. Each straight line segment is typically illuminated by a different light source so that different segments may be illuminated as desired to form different numerals. These numerals have an appearance similar to stenciled numerals. For displays that need to be switchable from one character to another, such as a digital time display, this is typically adequate.
Other displays only show a single character or a sequence of characters having a defined meaning such as a word, for example. An example of such an illuminated display is an electronic display for kitchen appliances that at different times illuminates one or more words such as “BAKE”, “BROIL”, “WARM”, or “HOLD”. It is typically desirable for such characters or sequence of characters to have a typeset character appearance without visible supporting members connecting the base to the inner members of the display for closed characters. For example, in the display for the word “BAKE” the letter “B” is a closed character with two enclosed inner members and the letter “A” is a closed character with one enclosed inner member whereas the letters “K” and “E” are open characters. If the supporting members that support the enclosed inner members of the display for the letters “B” and “A” are not visible then all four characters in the word “BAKE” appear to be typeset when the word “BAKE” is illuminated.
An approach to the problem of providing illuminated characters a typeset appearance is disclosed in U.S. Pat. No. 6,422,711 issued Jul. 23, 2002 to Chao et al. The Chao et al patent discloses an embodiment having a rib that functions to connect an inner member of a closed character to the opaque base of the display. The rib disclosed in the Chao et al patent protrudes from one surface of the base and therefore limits the usefulness of the approach.
Hence, an illuminated display where closed characters have a typeset character appearance without any visible members connecting the inner members of closed characters to the base of the display is desirable.